Apparatus for drying



March 22, 1927.

F. A. SECORD APPARATUS FOR DRYING Original Filed Oct. 30. 1919 2Sheets-Sheet 1 venioi": Fv'ederi'cicfl'ecord,

v 1.240 4 iM mg? 7 March 2 2, 1927. r

F. A. SECORD APPARATUS FOR DRYING Origihal Filed Oct. 50, 1919.

2 Sheets-Sheet 2 n Q Q 1 4. I

ll llllll lllllll Inventor:

Patented Mar. 22, 1927..

FEEDERICK A. SECOED, 01E PORTLANQ MAINE.

APPARATUS FOR DRYING.

Application filed October 30, 1819, Serial No. 334,476.

materially shorten the amountof time re-- quired for drying materials,such for example, as lumber and the like, without subjecting the same toactions or conditions likely to produce waste such as by checking.

The invention will be best understood by referring to the accompanyingdrawings, which disclose merely for purposes of illustration oneembodiment of an apparatus embodying this invention, the scope of thesaid invention being more particularly pointed out in the appendedclaims.

In the drawings Fig. 1 is a side elevation partly in section of thedrying apparatus;

Fig. 2 is a transverse section of the taken on the line 22 of Fig. 1;

, Fig. 3 is a detail plan of the carrier means for transmitting thematerial to be dried into the drying casing and for supporting the sameduring the drying operations, and

Fig. 4 is a detail plan section taken on the line 4L-4r of Fig. 2illustrating the water container which also contains the pipes formoistening and for heating the materials to be dried.

The methods heretofore employed in erying various materials andparticularly lumber have necessitated the extension of the dryingoperations over a. very long period of time and also have resulted in alarge percentage of waste due to many'r-easons but principally to thefact that the outer surfaces of the lumber became dry much quiclc erthan the interior, thereby causing an uneven shrinkageandconsequentchecking of said outer surfaces. Furthermore the contraction of the outer surfaces of the lumber results in the closing ofthe pores to such an extent as greatly to retard the completion of thedrying operations. Such defects were largely due to the subjecting ofthe materials to forced currents of air of high temperature which carrythe moisture away from the outer surfaces thereof faster than themoisture can be transmitted by capillary attraction from the interior toreplace that carried away by the drying medium.

The present invention contemplates the production and maintenance ofcertain ranges of temperature between the material that is being driedand the drying medium so as to maintain a more perfect equilibriumSilll'lG frame 3 provided with wheels 4 arranged Renewed August 12,1926..

between the vaporizing of the moisture upon the surface of the materialand the transmission of moisture from the interior portions of thematerial by capillary attraction, thereby avoiding the unequal contraction and the inevitable closing of the outer pores of said material. Inthe present example, therefore, means are provided for transmitting heatof a desired temperature to the material to be dried, and then insurrounding said material by or in subjecting it to the action of adrying medium, pref? erably of a lower temperature than that of saidmaterial, in order that the moisture at the surface of said material maybe rapidly vaporized .and removed. It is well known to those skilled inthe art that moistureladen materials when subjected to suddentemperatures will retain, due to the moisture therein, a temperature anumber of degrees below that of the heat-supplying means, but as saidmoisture is gradually removed from said material the temperature thereofwill more nearly approach the temperature of its heat-supplying sourceIn view of this gradual change in the temperature of the material, it isdesirable that the range between the surrounding drying medium and theheat supplying medium be maintained substantially uniform, and that thetemper.- ature of said drying medium be increased from time to time inaccordance with the changes in temperature of said material, and forthis purpose means have been provided for increasing the temperaturefrom time to time of the drying medium, which is admitted to andsurrounds the material that is being dried.

For producing the above results, I have, as will be seen by referring tothe drawings, provided a casing 1 of any suitable design or constructioncapable of enclosing the material that is to be dried. Although the saidcasing may be of any suitable length and contain various sections, thatillustrating the presentexample embodies only one section, which is of asuflicient length to contain a suitable carrier 2, herein consisting ofa to roll along tracks 5, 5, which extend longitudinally of thecasing 1. The carrier 2 is herein shown as comprising a perforated top 6upon which the material to be dried is piled in such a manner as topermit a circulation of air around the greater portion of the variousarticles that are mounted thereon. For example, in Fig. 2 the carrier isloaded with strips 7 of lumber arranged in layers, and each layer isseparated from its supporting layer by separators orwhat are commonlyknown as sticking 8 in the manner ordinarily used in piling lumber. Thevarious tiers of said lumber are separated from each other by verticalspaces 9, thus permitting the drying medium to circulate freely amongstthe various sticks composing the load upon said carrier. A carrier suchas described, together with its load, is then rolled into the casing 1and said casing is then closed up by means of suitable doors 10, 10arranged at opposite ends thereof or wherever desired, and the materialmounted upon said carrier is then heated to a desired temperature, whichtemperature may be varied according to conditions and to the nature ofthe material. As an example,

i however, let it be assumed that the temperaa above.

ture of the material is to be approximately 140, this, however, beinggiven merely as an example and not for purposes of l1m1ta tionand thepreferred method of heating said material being by radiation andtransmission, that is, arranged beneath the carrier I have provided acoil or coils 11, preterably steam pipe, which are heated to the desiredtemperature and the heat transmitted through the material of the carrierand through the perforations in the top thereof to said material. As thematerial to be dried is in the present state substantially filled withmoisture, a temperature considerably higher than that required for thematerial will be necessary in said coil in order to produce the desiredresults; but as said moisture is removed by the process hereinafterdescribed, the temperature of said material will gradually increaseuntil it more nearly approaches the temperature of the coil, which statewill not occur until the lumber is practically dry. By arranging theheating coils 11 close up to the bottom of the carrier, the heat will beim parted to said carrier and be transmitted therefrom throughout theseveral layers of lumber piled thereon, although naturally thetemperature of the various layersnvill gradually decrease toward the topof the load. lVhen the desired temperature has been reached, at'least inthe lower layers, the present method contemplates the supplying of adrying medium with as little pressure as possible to said casing.Obviously, as the lower layers of the material upon said carrier becomedry or approach a completely dried state, such layers will absorb agreater amount of the heat and thus be able to trans mit more of saidheat to the layers there- It is desirable that the drying medium that isadmitted to the chamber containing said material be admitted at pointswhere it will contact with the lower or hotter layers of material, andfor this purpose the casing is divided into zones, each zone having itsown drying medium supplying means consisting, in the present example, 01

pipes 12, 13, 14 and 15 respectively. These pipes, being in the presentexample tour in number, may of course be increased or diminished in sizeand number according to circumstances and to the dimensions of thecasing. The pipes referred to are herein shown as duplicated uponopposite sides of the casing and correspond in length with the sectionof the casing within which they are located, that is, they are madesubstantially the length of the carrier 2, but should a number ofcarriers be arranged in the easing, each carrier would have itsindependent supply pipes. The pipes 12, 13, 14 and 15 have suitabledischarge orifices 16 adapted to direct the drying medium against thematerial the-rebeneath. Each of said supply pipes is herein shown ascommunicating with a header 17 through suitable valves 18, whereby thesupply of drying fluid to each of said pipes may be out ofi. The header17 extends downwardly, and is connected with a supply pipe 19, throughwhich the drying medium is conducted from any suitable source not shown,said supply pipe being arranged in the present example centrally of saidcasing so that a uniform supply will be provided tor each side of thecasing. The coils 11 that are disposed beneath the carrier 2 arepreferably arranged within what is herein designated as a water tightcontainer 20, having suitable water supplying and discharging pipes 21and 22 respectively, whereby the said container may be flooded ashereinafter described. The container also has connection through a pipe23 with the supply pipe 19, and a valve 24 is arranged in this pipe toregulate communication with said supply pipe. The various pipes 12, 18,14, 15, 19 and 23 are, as heretofore stated, for the purpose ofconducting the drying medium to Various parts of the casing, and it isdesirable that this drying medium be maintained at a lower temperaturethan the material that is being dried, so as to produce the vaporizationof the moisture upon the surface of said material. For example, if thematerial in the lower layer or layers upon the carrier is approximately140 temperature, the drying medium may be supplied to said casing at atemperature approximating or thereabouts, although it is distinctlytobeunderstood that this range is given merely as an example, and notfor purposes of limitation. However, upon being delivered to the casing,said drying medium being cooler than the material, will. tend to settleand as it contacts with the warmer moisture covered surfaces of thematerial all of the moisture upon said surfaces will immediately takethe form of vapor, and being warmer than the drying medium will impartmore or less heat thereto. Furthermore said drying medium as itapproaches the heated area at the bottom of the casing will accumulatestill more heat and thereby beforced upward by the incoming coolercurrents, and will discharge through openings 25 arranged at the top ofthe casing. As hereinbefore stated, it is desirable that the dryingmedium be admitted to said drying chamber with as little pres sure aspossible in order not to carry away the moisture faster than the samecan be drawn by capillary attraction to the outer surfaces of thematerial, therefore the pressure of said drying medium is ver slight,only sufficient to carry it into said chamber where the difference intemperature between the same and that of the material and air thereinwill tend to cause said drying medium to settle to the bottom until ithas become sufficiently heated by the advanced temperature of thematerial to cause it to change its course and move to the top of saidcasing, where it will be discharged though the openings 25. To providethe desired force necessary to deliver the drying medium from its sourceto said casing, I have herein provided a blower 26 arranged at anysuitable point in the supply pipe 19, the speed of said blower eingvaried to increase or diminish the pressure or force of said dryingmedium. I have previously stated that the temperature of the materialwithin the casing that is being dried increases as the moisture thereinis removed, the presence of moisture in said material having a tendencyto depress or lower the temperature, and as said moisture decreases involume, the temperature increases in direct proportion. Obviously,therefore, where it is desirable to maintain a uniform range oftemperature between the material and the drying medium, means must beprovided for increasing from time to time the temperature of said dryingmedium. I have, therefore, in the present example provided means foraccomplishing this result, said means consisting of a conductor 27 whichmay be connected with any suitable source capable of supplying a dryingmedium preferably of relatively low temperature because it is moreconvenient to start with a low rather than high temperature. Forexample, where the drying medium is to be air, as it preferably is inthe present case, said conductor 27 may be connected with a suitablerefrigerating plant or it may be connected directly with the atmospherewhere the temperature of the atmosphere is below that required toaccomplish the desired results.

Uniting with said conductor 27 is a conductor 28, which I have hereinshown as connected with achamber 29 within which are arranged coils 80,preferably of steam pipe, whereby the air which is conveyed through saidchamber 29 and through said conductor 28 may be heated to the desiredtemperature. The conductors 27 and 28 are provided with suitable dampers31 and 32 respectively, whereby the desired proportions of hot and coldair may be provided in the conductor connecting said conductors 27 and28 with the blower 26. By these or other suitable means, a suitablytempered drying medium may be supplied to the easing, wherein is thematerial to be dried, and this drying medium may be constantly varied intemperature as the drying operations progress and thus a predeterminedrange of temperatures may be maintained between said material and saiddrying medium.

The arrangement of the casing and of the top plate 6 of the carrier,also the construction of the carrier are such as to confine most of theheat supplied by the coils 11 within the space beneath said carrier, sothat the heat therefrom, instead of being circulated upwardly throughthe casing, will be transmitted through the material surmounting saidcarrier to the several layers thereon. Naturally then the lower layerwill, as heretofore stated, be of a much higher temperature than thesuccessive layers thereon, and as the moisture is removed from the lowerlayers, said layers become more nearly the temperature of the said coilsand will, in consequence thereof, ra diate more heat to the succeedinglayers. In the present example, by providing the perforations in the topplate 6, some of the heated medium will be permitted to circulateupwardly through the spaces provided between the various layers of thematerial, and thus assist somewhat in the drying of the upper layers,and the air thus permitted to escape from the chamber at the bottom ofsaid carrier will increase the temperature of the drying medium as it isadmitted to the drying chamber and assist in changing the course of saiddrying medium, thereby increasing the carrying capacity thereof.

Obviously, the drying of the material. upon the carrier where the sameis of a considerable height may be greatly increased by providing thevarious zones, hereinbefore referred to, which correspond to thevariations in temperature of the layers of material upon said carrier,with supplying means whereby the tei'nperature of the drying medium tosaid several zones may be varied in temperature. Naturally, however,this will involve considerable expense because of the fact that each ofsaid zones will have to be connected with independent temperatureadjusting means similar to the conductors 2'7, 28 and coils 30. It is,however, within the scope and purpose of the invention to provide eachof the pipes 12, 13, 1a and 15 with temperature varying means ashereinbefore ill) iao

described, but in order to simplify the pres ent example, only one ofsaid temperature regulating devices is shown, and this in connectionwith the main supply pipe 19. lVhere only one of such means is provided,it will be most practical to begin the drying of the several layers uponthe carrier at the bottom and proceed upward layer by layer or by groupsof layers until the entire load is dry enough to be removed from thecasing. In carrying out this feature of the invention, 1 preferably shutoff communication between all of the pipes except the lower pipes 12,the valves 18 for all pipes except the pipes 12, and the valve 2% beingclosed during the first step of the drying process,

at which time the drying medium which is being admitted through saidpipe 12 is assumed to be about 70 in temperature, while the temperatureof the material that is being dried approximates ll-O these temperaturesbeing given merely for an example, as it will be obvious that they maybe varied according to the character of the material that is to bedried. lVith the material filled with moisture and heated to 140 it willbe obvi ous that the temperature of the heating devices or coils 11 willbe considerably higher owingto the fact that the moisture in thematerial has a substantial cooling effect, but as this moisture isremoved through vaporization by the subjection of the material to theaction of the cooler drying medium, which is now being admitted throughthe pipe 12, the temperature of said material will gradually beincreased until it approaches the temperature of the heating coils 11which are constantly transmitting heat to the said material. Upon theremoval of all of the moisture from the lower layers of the material,these layers will more readily transmit the heat from said coils throughthe layers of material next thereabove, and when these conditions arereached, communication between the lowermost pipes 12 will be cut offfrom the supply pipe 17 and communication between the next upper pipes13 be opened by opening the valve 18 therefor. Naturally the temperatureof the second or next upper layers of material will be less than thoseat the bottom due to their distance from the source of the heat, namely,the coils 11, and in order that the desired range of temperature bemaintained at this point, adjustment of the dampers 31 and 32 will nowbe necessary. l Vhen the drying of the material within the next zone,that is, that area controlled by the second set of pipes 13, iscompleted, communication between said pipes is shut off and the nextupper series will be opened and'the operation repeated, and so on untilthe entire stack of material has been dried.

It is within the scope and purpose of the invention to increase thetemperature of the coils 11 rather than to decrease in the desiredproportions the drying medium as it is being conducted to the severaltiers of pipes 12, 13, 1 1 and 15, the main object being to maintain apredetermined difference in the temperatures of the material and thedrying medium throughout the entire operation. As the air whichconstitutes the drying me dium becomes laden with moisture from thematerial and is carried upward by its increased temperature due to thecontact thereof with the heat arising from the coils 11, as well as fromits acquisition of moisture, it will pass to the upper regions of thecasing and escape through the openings 25 therein.

It is desirable to maintain the various tempe'atures hereinbeforedescribed com-.

paratively low in order that the lumber be not exposed to excessive heatso as to cause an unequal expansion between the outer and partiallydried areas and the inner moist areas. It is, however, a well-known factthat the lower the temperature of the air, the lower will be themoisture carrying capacity thereof. that air at 70 will carry abouteight grains of moisture to the cubic foot, while air at 180 will carryabout one hundred and sixty-six grains to the cubic foot. It would seem,therefore, that the higher the temperature the more rapid would be thedrying of the material. Such, however, is not the case, for whereexcessive heat is allowed to contact with the outer surface of the woodor other materials that are being dried, said outer areas will be driedso rapidly that the process of drawing the moisture from the interior bycapillary attraction will not keep pace with the removal of moisturefrom the outer surfaces. This results in an unequal contraction of thepores of said outer areas, thus greatly retarding the drying process andoften producing checks in the material; whereas a much slower removal ofmoisture from the exterior will maintain the drying forces inequilibrium, that is, the moisture will be removed from the outside nofaster than will the process of withdrawing the moisture from theinterior by capillary attraction take place. In order to speed up thedrying of the material without causing said results to take place. Ihave provided in the upper part of the casing a coil 34: preferably ofsteam pipe, which may be maintained at an exceedingly high temperature,much higher, if desired, than that of the coils 11, and as the naturaltendency of heated medium is to rise rather than settle, that heated bysaid coils 34 will pass upwardly through the openings 25, provided saidopenings are large enough, and out of the said casing and in so doingthe circulation of fluid within the casing will be increased and so willits temperature, and the temperature of the moisture laden air which Forexample, assume ill) is passing upwardly from the maternal toward thetop of the casing will likewise be increased by heat from said coils andthe moisture carrying capacity thereof Will be correspondinglyincreased. The hot air or fluid surrounding said coils 34 will form, as

it were, a blanket at the top of the casing Which assists in directingthe relatively cooler air entering through the several pipes 12, 13, 14and 15 downwardly against the material, and this air by cont-act withthe heated material will, as previously stated, acquire heat which willcause it to rise to the zone occupied by the coils 34 where addedimpetus will be given thereto to carry it out of the casing. Saidmoisture-laden currents of air in rising will, upon entering the zone ofsaid coils 34, be materially expanded and thus insure the carrying offof said moisture from the casing without permitting condensation to formupon the upper wall thereof.

I have illustrated the casing 1 as of a length suitable for receivingonly one carrier. It will, however, be evident that the length of thecasing may be varied either by increasing or decreasing the same and thedrying units varied to correspond with the length of said casingswithout departing from the scope and purpose of this invention.

Very often material will be brought to the casing for drying which hasbeen exposed more or less to the atmosphere, and has acquired acomparatively dry outer surface, the pores of which have becomecontracted and consequently the process of drawing the moisture from theinterior by capillary attraction will be materially retarded. It is,therefore, desirable to treat such material so that the best resuits maybe obtained from the process hereinbefore described, and one method oftreating such material is to provide a coating of moisture upon thesurface thereof. I have, therefore, for this purpose provided thewatertight container 20, into which water may be admitted, or as hereinshown, the entire casing is made water-tight so that it may be filledwith water if desired, and in connection with this I also provide aseries of perforated steam pipes 35, 35 interspersed among the variousloops of the coils 11, whereupon when steam is turned on vapor will risefrom said container when that only is filled with water or wheretheentire casing is filled the water therein will be heated to theclesired degree, thus softening and moistening the surface of thematerial to be dried. This coating of moisture also causes the pores ofthe material to expand and thereby start the process of removing themoisture from the interior to the exterior by capillary attraction.After sufficient moisture has been deposited upon the exterior of thematerial the steam may be shut off, the water drained and heattransmitted to the material from thecoils 11, after which the processhereinbefore described may be carried out.

There are occasions when the material that is to be dried is at a highertemperature than desired for beginning the steps of the herein describedprocess, it being necessary to reduce the temperature thereof, and foraccomplishing this result I have, as stated, provided a connectionbetween the container 20 and the main supply pipe 19, whereby air of apredetermined or desired temperature may be admitted to the saidcontainer and be transmitted through the plate 6 to the material restingthereon. It will also be obvious that the latter instrumentalities maybe utilized to convey the necessary amount of heat to the bottom of thepile of material in place of the steam pipes 11, all of which variationsare within the scope and purpose of the invention.

It has been stated that a certain range of temperatures is maintainedbetween the drying medium and the material to be dried, for the purposeof preventing too rapid drying and thus causing the checking or Warpingof material, and this is particularly the case in the drying of lumber.It should, however be understood that the method of drying is notlimited to the maintenance of this range of temperature throughout thedrying operation, for such a range may be increased at intervals whenall danger of warping or checking of the material is past, for example,in the drying of lumber the'starting of the process might be with thetemperatures not very far apart, say 20, and thus maintained until acertain'amount of moisture, 10%, for example, has been removed, afterwhich all danger of checking being past, the range may be increasedeither gradually or very abruptly, as desired, according to the natureor character of the material.

Obviously numerous other variations in the manner of supplying heat tothe material. may be made as well as in the manner of heating the dryingmedium, as for example, in certain instances the steam may be admitteddirectly to the casing through the perforated pipes 35, .35 withoutadmitting any water or liquid of any kind into the I casing orpermitting steam to pass upwardly through the openings in the perforatedplate 6 and into contact with the material upon the carrier.

It is also within the scope and purpose of the invention to supply steamto the various pipes 12, 13, 14 and 15. To accomplish this result I haveprovided a connection between the pipe 19 and the steam supply pipe 11,as shown in Figs, 1 and 4, which connection consists of a pipe 36 whichpipe is provided with a valve 37 whereby communication may be cut offwhen desired. 1

hen the'entire casing is to be flooded or filled with the solution fortreating the material to be dried, it is desirable that the numeroussupply pipes be closed so as to pre vent the solution from flowing backinto the supply pipe 19 and to accomplish this result the valves 18 and24 may be closed, said valves being arranged in such relation to theirrespective pipes that the desired result may be obtained.

The results produced by the above process are the material reduction intime of drying lumber or like substances, and the elimination ofchecking, twisting and Warping thereof, also the lumber so dried willnot be as brittle as wood dried by other processes, and in addition thematerial so dried Will be ready for immediate use. Although I havedescribed the above op erations in connection with the drying of lumberor like substances, it is distinctly to be understood that within thescope and purpose of the invention, other materials such asgrains,fruits, clay products, peat, and practically all substancesrequiring drying may be treated with equal success.

\Vhile I have herein shown and described merely for illustrativepurposes one specific embodiment of my invention, and have disclosed anddiscussed in detail the construction and arrangement incidental to suchdisclosure, it is to be distinctly understood that the inventionislimited neither to the mere details or relative arrangement of the partsnor to the specific application herein shown,

but that extensive variations from the illustrations may be made withoutdeparting from the principles thereof,

Claims. I

l. A drying apparatus having, in combination, a casing for the materialto be dried, means to transmit heat to said material, means to supply tosaid casing a drying 111B, dium having a relatively lower temperaturethan said material to effect the vaporization ofmoisture on saidmaterial and means to increase the temperature of said moistureladenmedium above the critical zone of the drying operations to facilitatethe removal of said moisture from said casing.

2. A drying apparatus having, in combination, a casing for the materialto be dried,

means to transmit heat to the material within said casing, means tosupply to said casing a drying medium having a relatively lowertemperature than said material to eifeet vaporization of the moisture onsaid material, and means to maintain a predetermined range oftemperatures between said drying medium and said material.

3. A drying apparatus having means to transmit heat to the material tobe dried and means to subject said material substantially at the sametime to the aetion of a drying medium having a relatively lowertemperature than saidmaterial, to eifect vaporization of the moistureupon said material.

4. A drying apparatus having means to transmit heat to the material tobe dried, means to subject said material to the action of a dryingmedium having a relatively lower temperature than said material, andmeans to maintain a predetermined range of temperatures between saiddrying medium and at predetermined sections of said ma.- terial.

5. A drying apparatus having means to transmit heat to the material tobe dried, means to subject said material during said heating operationto the action of a drying medium having a relatively lower temperaturethan said material, and means to increase or diminish the difierenoes intemperatures between said drying medium and said material,

6. A drying apparatus having, in combi nation, a casing for the materialto be dried,

means to transmit heat to the material within'said casing, means tosupply a drying medium to said casing, means to regulate the temperatureof said drying medium and means arranged at the top of said casing toincrease the temperature of the drying medium to facilitate thedischarge thereof from said casing.

7. A drying apparatus having, in combination, a casing for the materialto be dried, means disposed at the bottom of said casing to transmitheat to the material, means for supplying a drying medium at a pointabove said heating means, means to temper said drying medium and meansdisposedadjacent to the top of said casing adapted to impart heat tosaid drying medium to facilitate the removal thereof from said casin 8.A drying apparatus having, in combination, a casing for the material tobe dried, means to supply moisture to the surface of said material,means to transmit heat to said material, means for supplying a dryingmedium to said casing at a point above said heating means and means totemper the dr ing medium prior to its admittance to said casing.

9. A drying apparatus having, in combination, a casin for the materialto be dried, means to supply moisture to the surface of said material,means to transmit heat to said material, means for supplying a dryingmedium to said casing at a point above said heating means and means totemper the drying medium subsequent to its admittance to said casing andto facilitate the discharge of said drying medium from said casin 10. Adrying apparatus having, in combination, a casing for the material to bedried, a carrier adapted to be moved into said casing and to supportsaid material therein, means arranged beneath said carrier to transmitheat to the material supported ltltl thereon, means to supply a dryingmedium to said casing from a point substantially above said materialheating means, and means to temper said drying medium prior to itsadmittance into said casing.

11. A drying apparatus having, in combinat-ion, a casing having aplurality of openings at the top thereof, a carrier for conveying thematerial, to be dried to and from said casing, means arranged in saidcasing beneath said carrier to transmit heat to the material thereon,means to supply a drying medium to said casing at a point substantiallyabove said heating means, means to regulate the temperature of saiddrying medium and means arranged in said casing above the entering pointof said drying medium adapted to increase and facilitate the dischargeof said drying medium from said casin g through V the openings at thetop thereof.

12. A drying apparatus having, in combination, means to support thematerial to be dried, means arranged beneath said material to transmitheat thereto, and means to direct an exteriorly tempered drying mediumhaving a relatively lower temperature than said material, upon saidmaterial to effect vaporization of the moisture thereon.

13. A drying apparatus having, in combination, a carrier for thematerial to be dried, means to transmit heat to the material on saidcarrier and means to supply a drying medium having a relatively lowertemperature than said material at points progressing upwardly withrespect to said material to effect the vaporization of moisture on saidmaterial.

14. In a drying apparatus, the combination of a casing adapted tocontain liquid, a carrier for conveying the material to be dried to andfrom said casing, and means tov treat predetermined sections of thematerial supported by said carrier.

15. In a drying apparatus, the combination of a casing adapted tocontain liquid, a carrier for conveying the material to be dried to andfrom said casing, means to supply liquid to said casing, means to temperthe liquid while in said casing, means to remove the liquid from saidcasing, and means to supply tempered air to the material supported bysaid carrier.

16. In a drying apparatus, a liquid-tight casing, a carrier having aperforated bottom for supporting the material to be dried, means tosupply liquid to said casing to immerse the material therein and heatingmeans arranged in said casing to temper said liquid.

17. In a drying apparatus, a liquid-tight casing, means to supply liquidto said casing,

a plurality of air supply pipes connected at different levels with saidcasing, and means to close said air supply pipes to prevent thedischarge of liquid from said casing.

18. In a drying apparatus, a casing and a pipe connected with saidcasing for supplying either a highly tempered drying medium or a lowtempered drying medium through said pipe to said casing.

19. In a drying apparatus, the combination of a casing, a plurality ofair pipes c0nnected at predetermined levels with said casing forseverally supplying a drying medium thereto, and means exteriorly ofsaid casing to regulate the temperature of the air supplied to saidpipes.

20. In a drying apparatus, the combination of a casing and a series ofair pipe lines extending along the sides of said casing at predeterminedintervals apart to supply relatively low tempered air to said casing,and means to temper said air prior to its delivery to said casing.

21. A drying apparatus having in combination, a casing for the materialto be dried, means to transmit heat from the bottom of said casingupwardly through the material, means for supplying a drying medium tosaid material from a point above said heating means, means to tempersaid dryingmedium, and means disposed adjacent the top of said casing toimpart heat to said drying medium and to facilitate the removal thereoffrom said casing.

22. In a drying apparatus, the combination of a casing, a carrier forconveying the material to be dried to and from said casing, and means tosupply a heating medium to said casing either in the form of heated air,or steam or water.

28. In a drying apparatus the combination of a casing provided with adrying chamber and means to provide a fluid from a mixture of selectedportions of hot and relatively cold fluids and to supply the temperedfluid to a plurality of zones in said drying chamber.

24. In a drying apparatus, the combination of a casing having a dryingchamber, means to transmit heat to the material with in said chamber,means to supply a drying medium to said chamber and means to provide arestricted discharge of the heated 1noisture-laden drying medium fromthe top of said chamber to assist in depressing the incoming dryingmedium to the lower parts of said chamber.

Iii testimony whereof, I have signed my name to this specification.

FREDERICK A. SECORD.

